The present invention relates to a retinal implant.
An implant according to the generic type is known from U.S. Pat. No. 5,935,155. This document proposes that a functional unit (IGF) positioned inside the vitreous chamber be connected to an externally positioned functional unit (EPF) via wireless coupling of two coils. The coil of the internal functional unit is in this case arranged in the lens behind the iris.
In addition to the surgical intervention on the vitreous body for implanting the functional unit (IGF) positioned inside the vitreous chamber, a second surgical intervention is necessary in the anterior eye section for implanting the coil or a second functional unit (AGF) positioned outside the vitreous chamber (especially in the lenticular capsule in place of the intraocular lens (IOL), which needs to be removed beforehand).
The second functional unit (AGF), which is implanted in the lenticular capsule and is provided, in particular, in the case of various retinal implants, is mechanically connected to the IGF via a microcable and, in currently available versions, cannot be temporarily separated and re-connected. Technical solutions for this are, however, available. This mechanical connection makes the surgical interventions significantly more difficult since, when implanting the AGF in the lenticular capsule envelope, it is also necessary to make an opening in the lenticular capsule wall and to transfer the IGF, with the microcable connection, through this opening into the vitreous chamber. This entails additional risk factors such as: mechanical destabilisation of the lenticular capsule envelope by the additional opening; mechanical stress on the implant components, including the microcable; lengthening of the implantation time; increase in the risk of future pathological tissue changes, which may make the implant function or further surgical interventions (such as e.g. re-explantation) difficult or impossible.
Positioning the AGF in the anterior eye segment significantly restricts optical access to the retina and to the IGF. This can have a detrimental effect both on the function of the implant system and on sight, as well as on the medical inspectability of the vitreous chamber.
Externally positioned functional units (EPF) located outside the body are positioned immediately in front of the eye, in the normal field of view of the eye, in place of a spectacle lens or a contact lens, and hence impede any partial sight which may still remain (e.g. in subjects with macular degeneration and remaining extrafoveal vision). As the signal processing effort rises, especially in the case of retinal implants, when the number of microcontacts increases, the mass and energy demand of the microelectronic components rises significantly, so that in this context a limit for intraocularly implantable functional units is rapidly reached and the desired functional quality of the implant is thereby substantially restricted.